Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

insulating an old house


xfrank12's Avatar
Visiting Guest

Posts: n/a

08-15-02, 10:01 PM   #1  
xfrank12
insulating an old house

about 70 years ago a bunch of farmers got drunk and built my house. over the next 30 years they added on to the house every time they got drunk untill the town enacted zoning laws and they were forced to stop adding on without giving any thought to what they were doing.
i would like to insulate this house. since i have a story and a half with both a finished and an unfinished attic plus second story crawl spaces, i am a little confused.
can fiberglass insulation be placed against the roof in any room. in other words, the only thing between the insulation and the roof shingles is the 1" thick boards the shingles are nailed to. if the answer is no, how am i supposed to get an R value that comes close to what it should be ? my roofs ,i have 2 upstairs , are 2 x4 . since my first floor, floor and my second floor, floor are 2x6, should i try insulating them to compensate for the attic ? i live in Conn. they recommend R 49. with 2x4's i can only use R 15. compressing the insulation to leave a space for ventalation, im down to about R 10.
any ideas ? besides hiring an arsonist. or praying for a flood.
no, i didnt buy it. my father left it to me . thanks.

 
Sponsored Links
resercon's Avatar
Member

Join Date: Nov 2001
Posts: 1,873
NJ

08-16-02, 12:01 PM   #2  
There are 2 major considerations here. The first is doing the insulating without causing any harm to the structure and the other is meeting building code.

Those 1 inch slats you are refering to are there for a purpose. You apparently have wood shingles. The slats allow the wood shingles to dry out properly when they get wet. What that means is if you were to insulate under them without providing some type of ventilation, they (wood shingles) would probably warp or cup as a result.

The second consideration is meeting building code. Each town has different building codes and are usually fair and reasonable. Since the structure was built before the enactment of those building codes and you are not remodelling, more than likely, those codes cannot be enforced. In other words, if you are not physically changing the structure, just merely adding insulation to it, those codes are probably recommended and not enforced. It is only prudent that you check with your local building inspector. You must be clear that you have no intention to remodel the structure, you just intend to insulate it.

Each town have their own building codes. Even though they have a state wide standard, depending upon the type of building stock you have in your town, will determine if codes have been added or upgraded. Once you have determined what is permissible in your area, I can assist you in methods that will get you the best performance from installing the insulation.

 
xfrank12's Avatar
Visiting Guest

Posts: n/a

08-16-02, 02:16 PM   #3  
xfrank12
im sorry. i dont think i made myself clear about the 1" boards you referred to as slats. i have asphalt shingles nailed to 1" x 5" tongue and groove boards. as for building codes, i already checked. i am exempt. as long as i dont do any major renovations.

 
resercon's Avatar
Member

Join Date: Nov 2001
Posts: 1,873
NJ

08-16-02, 03:46 PM   #4  
In the finished portion of the attic, I would recommend Kraft faced R-13 fiberglass insulation that goes up against the roof. I would also recommend you install a styrofoam baffles first to assure air flow between the insulation and the roof.

In the unfinished portion, I would recommend Kraft faced R-19 under the floor in the attic. If it is not floored, you could add as much insulation you like.

The wall between the finished and unfinished portion in the attic should also be insulated. I would recommend Kraft faced R-13 fiberglass insulation.

At the bottom of this message is a www icon, if you click on it, it will bring you to my site. If you read topic Insulation it explains how "R" values work. You'll see your largest savings come from the low "R" values. (ex. R-1, R-2, etc.) As the R-value # becomes larger, the savings diminish. This is referred to as the Law of Diminishing Return. You might find the topics Ventilation, Air Boundary and Thermal Boundary useful in your project.

 
xfrank12's Avatar
Visiting Guest

Posts: n/a

08-16-02, 04:03 PM   #5  
xfrank12
my roof rafters are 2 x 4. subtract 2" for ventalation, 1" the baffel and my R 13 is compressed to 1". which lowers my R to , what ? R 8, R 10? do i have the space ? can fiberglass be compressed to 1" ?

 
resercon's Avatar
Member

Join Date: Nov 2001
Posts: 1,873
NJ

08-16-02, 09:18 PM   #6  
The baffle will provide the ventilation, which will allow for 3 inches of insulation. Though it doesn't seem like much, it will suffice under these conditions. Your other alternative here is to use 3 inch thick rigid board insulation. It may provide for a slightly higher R-value.

 
xfrank12's Avatar
Visiting Guest

Posts: n/a

08-19-02, 08:44 AM   #7  
xfrank12
thanks for the advice, but i still dont understand how the baffle is going to allow me to use 3" of insulation. i have always been a visual learner though. i will have to go to the store and see a baffle to understand what you are saying.

would lowering the ceiling be an option? i could add 2 X 6 do the rafters, that would give me room for 6" insulation and stiill have 3" for ventilation. is there any reason why i would not want to lower the ceiling ?

 
resercon's Avatar
Member

Join Date: Nov 2001
Posts: 1,873
NJ

08-19-02, 08:09 PM   #8  
You could sister 2x6's to the existing rafters, but it seems to me like an awlful amount of work. If dropping the ceiling is feasible to you, then I would suggest you do the following;

1. The styrofoam baffles assures a channel for air to flow from your eaves to your ridge or gable vents.

2. The unfaced fiberglass insulation goes next. This will fill in the cavity between the rafters. Up against the baffles but not to extend past the rafters.

3. If you use 1 inch thick rigid fiberglass insulation, use hot glue to hold the rigid board to the rafters. Use aluminum foil tape to seal the joints. You can apply the boards in layers but you can't do more than 3 layers.

4. Then 1x2 wood slats are installed perpendicular to the rafters. This is used to permanately hold the rigid board insulation up and provide for a nailing surface for the sheet rock. They should be installed 16 inches on center. Make sure you use screws long enough to go through the slats, rigid board insulation and at least an inch into the rafters.

You'll find this is a much better method than sistering 2x6's and you'll get better insulating performance.

 
Search this Thread